<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>Document</title>
</head>
<body>
	type: function( obj ) {
		if ( obj == null ) {
			return String( obj );
		}
		// Support: Safari <= 5.1 (functionish RegExp)
		return typeof obj === "object" || typeof obj === "function" ?
			class2type[ core_toString.call(obj) ] || "object" :
			typeof obj;
	}
</body>
</html>
<script src='jquery源码分析.js'></script>
<script>
	alert(typeof null);
</script>